Perhaps you should try some spelling variations:
trinh trong » trinh truong, tranh trong, trinh trung
trinh quan » tinh quang, trinh luat, trinh han
trong xuan » truong xuan, trong quan, thong xuan
hieu suat » hieu luat, hieu qua
van hieu » cao hieu
xuan can » xuan cang, xuan tan, xuan chanh
can kien » van kien, cau kien, cap kien
kien hoa » dien hoa, tien hoa, kien ha
luan » lan

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( trinh quan luan van hieu suat ) or ( trinh trong xuan can kien hoa ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh quan luan van hieu suat ) OR ( trinh trong xuan can kien hoa )).
• Adding a wildcard symbol may retrieve word variants: (( trinh quan luan van hieu suat ) or ( trinh trong xuan can kien hoa ))*.